1. Field of the Invention
This invention relates to a sheet ejection apparatus built in a sheet processing apparatus including an image formation apparatus such as a copier or a printer as a part of a processing apparatus main unit and in particular to a sheet ejection apparatus intended for easily changing the number of ejected sheets that can be stored and a sheet processing apparatus using the sheet ejection apparatus.
2. Description of the Related Art
As this kind of sheet processing apparatus in a related art, taking an image formation apparatus as an example, an image formation engine containing a photo conductor drum, etc., for example, is installed in an image formation apparatus main unit (processing apparatus main unit), a sheet supply unit and an ejection tray are placed in the processing apparatus main unit, the image formation engine is formed with a sheet transport passage from the sheet supply unit to the ejection tray and forms an image by electrophotography, for example, and the image formed by the image formation engine is transferred to a sheet of paper, etc., supplied from the sheet supply unit, and then the image is fixed on the sheet by a fuser and the sheet on which the image has been fixed is ejected to the ejection tray.
In this kind of image formation apparatus, a sheet ejection apparatus is built in the exit of the processing apparatus main unit.
As a sheet ejection apparatus in a related art, a unit comprising paired ejection rolls built integrally in the exit of a fuser unit, for example, is used.
To increase the number of sheets that can be stored in an ejection tray, a sheet ejection apparatus comprising an upper ejection tray and a lower ejection tray for distributing ejected sheets to the upper and lower ejection trays is already proposed such as in JP-A-2000-302311 (see Mode for Carrying out the Invention, FIG. 1).
However, in this kind of sheet ejection apparatus, the sheet ejection position to each ejection tray is uniquely fixed and thus the number of ejected sheets that can be stored in each ejection tray is inevitably limited, and it is difficult for the user to change the number of ejected sheets that can be stored.
For example, in the art disclosed in JP-A-2000-302311, as two ejection trays are provided, the number of sheets that can be stored is increased as compared with the type wherein one ejection tray is provided, but the number of sheets that can be stored in each ejection tray cannot be changed. Thus, if the user wants to drastically increase the number of sheets that can be stored in each ejection tray, a large-capacity sheet storage unit must be retrofitted or the image formation apparatus must be changed to an image formation apparatus of a large-capacity model.